The objectives of this randomized, double-blind, placebo-controlled study are to evaluate the efficacy, safety, and tolerability of BRL49653C when administered once daily to patients with Non-Insulin Dependent Diabetes Mellitus (NIDDM) who are inadequately controlled on at leastt half-maximal dose(>10 mg/day) of glyburide. The primary endpoint will be reduction in baseline HbA1c after 26 weeks of treatment.